Congrats on the promotion 😉
Please take a look at the default extensions on this forum. It has a couple of anti-spam plugins. Normally, human bots are beaten only through an IP ban. CAPTCHA can block most of the bots. I am never a fan of deleting accounts. Consider it a log and move the spam posts to an admin-only tag. Then an indefinite ban on the user can be helpful. If they have any attachments, even images, it is better to remove them.